Dear Ms. Forester,
Thank you for posting your request on History Hub!
In addition to the advice from the previous poster, we suggest that you contact the Maryland State Archives to obtain a list of Dundalk/Baltimore orphanages operating in the 1940s. Then please contact the institution to request a record search or search any records from the orphanage that may be held by the Archives.
Residents of orphanages are listed in the federal decennial census. We searched the National Archives catalog and located the Population Schedules for the 1940 Census in the Records of the Bureau of the Census (Record Group 29) that may contain the residence of your grandfather if he was living in an orphanage in 1940. The 1940 Census schedules are digitized and available using the Catalog.
For information about the U.S. Census, see the Census Bureau technical documentation and questionnaires as well as NARA’s page on Census Records.
You may wish to search Ancestry.com or FamilySearch.org for the U.S. Census. There may be a fee for using Ancestry. Instead, please check for access at your local library as many library systems subscribe to these sites, making them free for their patrons.
We hope this is helpful. Best of luck with your research!